An Organic Light-Emitting Diode (OLED) is a display device capable of autonomous luminescence from a luminescent material driven by electric current. The luminescent material conventionally used in an OLED device is small molecules in form of dyes or pigments. These small molecules are deposited on a substrate in a particular pattern by means of a vacuum evaporation process.
As shown in FIG. 1, a current mainstream OLED device structure consists of an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer and a cathode. Therein, except for the cathode or the anode to be made of a metal material, the others are all made from organic small molecules.
Most of the prior art methods for improving a luminescence efficiency of the OLED devices are to replace the materials of the organic layers or to add different deposition layers. However, in a prior art vacuum evaporation process, the evaporation process for each layer needs to be completed in a separate chamber. At present, a length of around 10 hours in time will be needed, as a rate stabilizing period, for a material to attain a stable evaporation rate, and accordingly, the prior art methods of changing the OLED device structure for improving the luminescence efficiency would lead to cost increase and extended period of the evaporation process.